An electronic whiteboard having a function for taking in handwritten information written by hand on a surface of a display and a function for displaying the handwritten information is known in the related art. Contents written on the display surface of the electronic white board by a user's hand are accumulated as coordinates data, and the electronic white board draws the contents on the display as a stroke in which the coordinates are connected. Thus, similar to a conventional whiteboard, the user can draw letters, figures and the like. Further, the user can store the handwritten information and transmit the handwritten information to another electronic whiteboard via a network.
By the way, similar to a typical display, the user can adjust video settings such as a contrast and color temperature in the display contained in the electronic whiteboard such that an image on the display becomes easy to be viewed. However, for example, the video setting such as the contrast set by the user is not necessarily appropriate. PTL 1 discloses a technique in which, in order to prevent inappropriate adjustment by the user, a display stores an initial value of the video setting in advance, and the video setting is returned to the initial value in accordance with a user operation. PTL 1 discloses a contrast adjustment apparatus for returning the setting of a contrast to the initial value in a case in which a long pressing operation of a key is detected.